Forage harvesters operate in a well known fashion in a field of windrowed or standing crop material and include either a self propelled or pull-type base unit with a header attached thereto for cutting or picking up crop material and feeding it rearwardly. Typically, the base unit includes a forward generally rectangular inlet opening for receiving crop material from the attachment, a feeding assembly spanning the width of the inlet opening for conveying material into the base unit, and a rotating cutterhead for receiving crop material from the feeding assembly and chopping it into appropriate particle sizes. Some units employ a blower for transferring the chopped material via a discharge spout to a vehicle for transporting it from the field, while others utilize the throwing action of the rotating cutterhead to convey the chopped material up a discharge spout.
One commonly known arrangement is the use of a pull-type forage harvester in combination with a tractor and a forage wagon. The tractor pulls the harvester and wagon in tandem with the wagon hitched behind the forage harvester for collecting chopped crop material that is being expelled from the spout. Representative equipment of this nature is illustrated by the disclosure in U.S. Pat. No. 3,818,955, issued Jun. 25, 1974 in the name of Joseph M. Kline. Another well known example of a pull-type forage harvester used in combination with a forage wagon attached thereto is disclosed in U.S. Pat. No. 3,786,945, issued Jan. 22, 1974 in the name of Dean Homer Symonds. Insofar as self propelled units are concerned, a common arrangement is illustrated by U.S. Pat. No. 4,376,609, issued Mar. 15, 1983 in the name of Carl E. Bohman, et al.
Regardless of the type of unit being used, it is beneficial to couple the wagon to the harvester with a hitch assembly having a latching mechanism releasable from a remote location, such as the tractor cab in the case of a pull type harvester or the harvester cab in the case of a self propelled harvester. This enables the operator to quickly and conveniently release a full wagon and prepare to attach another wagon during field operation.
In the past, remote actuation of the coupling mechanism has been accomplished by using a rope or a cable directly connected to a spring loaded latching element mounted at the rear of the forage harvester. This has been fraught with various problems generally symptomatic of the use of cables and ropes in various actuating arrangements. Routing the actuating element through the cab wall of a tractor or self propelled harvester is difficult to accomplish while still maintaining the integrity of the element, i.e., avoiding excessive wear from crimping, twisting and snagging. Further, problems have been encountered during prior efforts to design a system that provides sufficient force to overcome force exerted by the hitch pin on the latching element. This is especially prevalent under conditions where the wagon being decoupled is downhill from the harvester.